Scarleteen

Is it okay to kiss someone with a canker sore (not a cold sore) that’s in the mouth? And how about giving oral sex with a canker sore?

The person with the canker sore may find that kissing or oral sex are uncomfortable or painful, depending on the location or severity of the canker sore, but to my knowledge there's no active risk in either activity. The person with the sore might find it helpful to rinse their mouth with a mild salt water solution afterwards.

Ok. Do canker sores result from oral sex or is it something else?

They can be caused by a lot of different factors, including intense stress, some vitamin deficiencies, and minor injuries in the mouth. It's not always possible to know what caused a particular sore, since there are a lot of possibilities, but oral sex isn't something that causes them so you can rule that out as a cause.